OpenEuphoria

RE: Alpha Blending with EuAllegro

• Posted by Brian Broker <bkb at cnw.com> Jul 09, 2004
• 517 views

I wrote:
> 
> Lewis Townsend wrote:
> > 
> > 
> > Howdy Brian Broker
> > 
> > >.. transparency in a percentage or something.  
> > > I'll check it out and get back
> > > to you (likely after the holiday).
> > 
> > Ok, its after the 4th of July. or was that not the holiday you were 
> > talking about ;-P
> > 
> > > I lost interest because it didn't seem like many others had much 
> > > interest
> > > (and I think that's also why Ray lost interest...).
> > 
> > Well, I'm interested since Euallegro seems to be the best solution to my 
> > 
> > 
> > graphics needs.
> > 
> > > I'll swing my focus back that way and see what I can do to help.  >Maybe 
> > > 
> > > 
> > > you can help me revive this nice platform for Eu.
> > 
> > I'll try. 
> > Do you think I should release demos of my game every time I make a major 
> > 
> > 
> > advancement? 
> > It might help with public awareness of the Euallegro library. :)
> > 
> > later,
> > LewyT
> 
> My bad, I got caught up in some Win32Lib testing again.  As far as 
> releasing demos... I wouldn't mind a preview to see if I can easily 
> convert it to my version of the lib.  It might also help me to figure 
> out the best solution for what you want to do.
> 
> Thanks,
> -- Brian
> 

Well, since I haven't heard back from you, I'll assume your program 
isn't ready for consumption.  Playing with my Allegro wrapper I came up 
with the following.  There might be a better way but this seemed to at 
least work:

-- note: alpha is a value between 0 and 255 --
procedure stretch_trans_sprite( atom bmp, atom sprite, integer x, 
integer y, integer size, integer alpha )
   integer nx, ny
   atom newsprite
 
   nx = bitmap_w(sprite)*size
   ny = bitmap_h(sprite)*size
   newsprite = create_bitmap( nx, ny )
   clear_to_color( newsprite, getpixel(sprite,0,0) )
   stretch_sprite( newsprite, sprite, 0, 0, nx, ny )
   set_trans_blender(0,0,0,alpha)
   draw_trans_sprite( bmp, newsprite, x, y )
   destroy_bitmap( newsprite )
end procedure

Let me know if this suits your needs...
-- Brian